Field of the Invention
This invention relates generally to a tarpaulin support device for semi-trailers, and more particularly, but not by way of limitation, to a tarp bow that is flexible and has more than one layer.
Description of the Related Art
As noted in Stephens et al., U.S. Pat. No. 5,664,824, incorporated by reference herein, tractor trailers used to haul loose material, such as sand and gravel, will often employ a tarpaulin cover over the open top of the trailer having a bottom and a pair of opposed side walls. The tarpaulin discourages any of the loose material from falling or being blown off during transportation. A series of curved bows extending laterally across the open top form a support for the tarpaulin. Use of a tarpaulin which is arched at the center provides a number of advantages. Rainwater will run off of the load more easily. Additionally, the arched center accommodates high loads. In the case of sand and gravel, loading of these materials is often preceded by removal of the bows in order to avoid damage. Loading of these materials through the open top will often dent, twit, and break the support bows.
Stephens et al. solves this problem by making the bow flexible. Specifically, Stephens et al. teaches a tarpaulin support device for an open top of a trailer, vehicle, or the like, where the device includes a flexible and resilient pole made of nylon composite which, although sturdy, is both flexible and resilient. The pole is normally straight but, when installed, bows outwardly away from the floor of the trailer. The pole will flex and deflect if sand, gravel, or other materials impact the pole during loading operations or in the event of impact from an end loader or other loading equipment used during the loading operation. Thus, the pole may be kept in place during loading of the trailer.
The pole of Stephens et al. is mounted to the trailer via opposing brackets, where each bracket is attached to the trailer and each has a non-cylindrical opening therein. A first socket and a second socket each have a receptacle to receive one of the pole ends, each socket terminating in a non-cylindrical post receivable in one of the openings to retain the sockets and retain the pole and to prevent radial movement of the pole.
Despite its many advantages, there are certain drawbacks to the Stephens et al. device. Notably, the nylon of the pole tends to become rough through use, causing the tarpaulin to wear and eventually tear. Additionally, the nylon tends to crack in both cold and heat. The nylon pole can be costly to replace, particularly considering the fact that a single trailer requires multiple poles. Another drawback of the Stephens et al. device is that, over time, it tends to cause the walls of the trailer to deflect outward.
Based on the foregoing, it is desirable to provide a flexible bow that provides the advantage of the Stephens et al. pole without the drawbacks stated above.